Engine



pt. 16, 1 J. P. BUTTERFIELD 2,610,615

ENGINE F iled March 24, 1948 5 Sheets-Sheet 1 (a: BY

A'r'roRNEYs.

p 1952 J. P. BUTTERFIELD 2,610,615

ENGINE 5 Sheets-Sheet 2 Filed March 24, 1948 IN V EN TOR. Fzlzfierfz elaf EB gwflm J. P. BUTTERFIELD ENGINE Sept. 16, 1952 Filed Marqh 24, 1948,

5 Sheets-Sheet I5 a I INVENTOR JZ/m FZaZZeI-fiL-ZZ F: i 5.5 ATTORNEYS Sept. 16, 1952 J. P. BUTTERFIELD 2,610,615

ENGINE Fil ed March 24; 1948 5 Sheets-Sheet 4 g: [a 4a I I N V EN TOR. Jain 2 ,Ba flar/z 29/42 Sept- 16, 1952 J. P. BUTTERFIELD ENGINE Filed March 24, 1948 7d 1e Qnnnnm 55 WIIIIIIIM 5 Sheets-Sheet 5 JNVENTOR.

/ BY if Patented Sept. 16, 1952 UNITED STATES PATENT OFFICE s V I 2510,615 I a g e ENGINE V a John P. Butterfield, Grosse' Pointe Woods, Mich assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application March 24, 1948, Serial No. 16,645

This invention relates primarily to internal combustion engines of the double acting type.

In the double actingtype'of engine'ja' double ended piston is employed for reciproca'tory move.- ment ina working cylinder, such engines being arranged to .provide. a combustion chamber at each end-'of each cylinder .fo'r cooperation with one end of the double ended piston, ,Engines of this general type'a're known in the art"'and" employ a crankshaft which" is directly operably connected to the double ended pistonj without the use of. a connecting rodfof the moreconventional type'ofzen'gine; v

It is an object .of. my inventio'n'to provide an engine having improved compactness forla given voutput whereby in comparison with knownjlengines of equivalent'output, an engine constructed in accordance withmy invention. occupiesfconsiderably less space. Such an engine isv desirable for many uses, as, for example, for driving motor vehicles whereinspace saving, along with Weight and cost reduction are constantly- 'striven for. v Anotheriobject is to provide an engine'of'improved simplicity of partsjespecially jin'Lconnection with a double acting" ty p'eof engine...

A further objectormy invention is to provide an improved 7 double, acting engine" having". its parts soarrahged as to provide improved'mechanical'relationshipsof the parts and atthe same time minimize "the overall dimensions of the engine for. an engine of a given displacement.

Further objects of inn-invention in its" more limited aspects, are 1 to lprovid'e aidouble acting engine of improved. compactness .in which, notwithstandin the necessity" for the. crankshaft to extend through. the doub1e' .ended. piston;.-'such crankshaft is or. the unitary .or one-piece forged type the. piston rings do, notovertravel the slots or openings in the cylinder, such openings being provided to accommodate the crankshaftjlbean ings or swing of the bearing block structurejthe double ended 'pi'ston is of Luniform'diam'ete'r as is the cylinder. .infwhich fthe piston slides; the piston intermediate body structure. providing 'the ties between the piston endslies within thejcylinder bore; and the crank as well' .as1a t least those portions of the bearing block win n are disposed immediately adjacent the piston sli'deway are so arranged as to at'all times lie' within thejcylinder bore although intermediate portions of the bear ing block may swing outsidethe' cylinder bore while still preserving the benefits of compactness. In addition, in order that the optimum of com:

lClaim; (61.123-56) pactness and engine output be obtained, I prefer ably locate the innermost piston ring of each piston head of theidouble ended piston as closely as practicable to the oblique portions of the unitary crankshaft and'to the cylinder block'openings for'the crankshaft bearings andthe intermediate portions of the bearing block when such piston head is in the extreme limit of its stroking movement inwardly..

In carrying out my invention, I'have provided, as a further object of my invention, a double acting engine of relatively large bore stroke ratio which is most desirable for compactness while at the same time realizing all the'other objects of my invention including the incorporation of a unitary crankshaft. Heretofore, in engines of this type, ithas been deemed necessary to provide a relatively small bore stroke ratio at a sacrifice of compactness or to incorporate structural arrangementssuch as a built-up or sectional crankshaft at a sacrifice of other desirable characteristics. This is especially so in connection with engines dealing with conventional high gas explosion pressures and while my invention is primarily directed to such engines it may also be of advantage in other machines utilizing unusually high pressure operation in the order of engine pressures rather than ordinary pressures usually dealt with in compressors, for example. However, generally speaking, compressor problems are quite diiferent from engine problems and many arrangements acceptable for compressors would result in failure if employed in modern engine structures or in other high pressure machines. 3

Another object is to provide an improved engine of the aforesaid type incorporating a solid or one-piece crankshaft in conjunction with a novel arrangement of engine assembly embodying a built up piston structure and built-up bearing block structure. In the copending application of Alexander G. Herreshofi, Serial No. 16,801, filedMarch24, 1948, certain of the broad principles and novel features incorporated in my disclosure are more particularly described and claimed. However, in said Herreshoff application there is incorporated .a multi-sectioned or built-up crankshaft to facilitate assembly of the engine. My' invention permits the use of the stronger and generally more desirable unitary crankshaft while; at the same time, incorporating novel features. of construction whereby the engine maybe readily assembled and whereby the essential desirable features of said Herreshoii application may be retained in my invention.

An additional object of my invention is to provide an improved bearing block structure capable of ready assembly with a crankshaft of the unitary type.

Another object'is to provide a double acting engine arranged for improved installation in a motor vehicle by reason of a novel construction and disposition of the cylinder block, camshaft, pistons, and oil reservoir.

An additional objectis to provide an improved and simplified assembly of engine block, crankshaft, piston, and bearing block components.

Yet another object is to provide an improved lubricant drainage from the valve chamber, above the pistons, to the oil reservoir below the pistons by utilizing the cylinder openings which accommodate the travel of the bearing block.

Further objects and advantages of .myinvention reside in the novel combination and arrangement of parts, more particularlyhereinafter set forth, reference being made to the accompanying drawings in which:

.Fig. .1 is .a longitudinal sectionalgplan view through -a portion .of theengine;

Fig.2 is. atransvers'e sectional elevational view through a typical-cylinder of. the Fig. 1 engine;

,Fig. 3.is a sectional view of'the left hand piston. and slid'ehead cr'lbearing block in their Fig. 1 positions, the view being taken as indicated by sectionline 3-.3 :ofFig. 1;

Fig. l is a transverse sectional view taken along line 4-4 of Fig.1? but showing the bearing block ofthe piston at the left end of'Fig. l in one of. its extreme .positions of movement laterally 90 from theposi'tion. of Figs; 1 and 3, portionsof the ,camshaft being also shown;

. Fig. 5 is a diagrammatic view illustrating the motion .of the bearing 1 block relative to .the piston;

Fig. 6 is a view similar to Fig. '3 but showing the piston in its mid-stroke position;

Fig. 6A is a diagrammatic perspective view of the crankshaft;

Fig.7 is an elevational view of atypical crank portion of the crankshaft asviewedaccording to line "i-'i of Fig. 4;

Fig. '8 is a sectional view taken on line's- 8 of Fig. 7;

Fig. 9 is a sectional view taken .on Iline9'9 of Fig. '7;

Fig. 10 is an enlarged elevational view of the bearing 'block'structure as seen in'Fig. 3, parts being broken away;

Fig. .11.is an'end elevational view according to the arrow H of Fig. 10;

Fig. 12 is. a view similar to Fig. 10 but illustrating .a modified bearing block, structure;

Fig. 13 is an end elevational view according to the arrow 4 3 of Fig. 12.

In the drawings, reference character A repre sents the engine crankshaft'structure which is formed as a solid, unitary, .or one-piece. steel forging. This. crankshaft structure has a plurality of central .axiallbearingportions l5 and the off-set crank portions it. The number of cranks It depends. onthe number of cylinders of theengine, there being onIcrank for asso- I ciation with each cylinder. Eachcrank isjoined with a pair of. adjacent bearing'portions. [.5 by obliquely extending. crankshaft portions I l Each of the cranks I6 is embraced by a slide head structure or bearing block structure 13 which has a split cylindrical bearing insert 13 having an internal cylindrical bearing surface l9 having a bearing fit witha crank it and a pair of diametrically disposed bearing surfaces 2G, 21 having a sliding fit in the slideway C- of a double ended piston D. This slideway extends transversely of the common piston and cylinder axis 22 and the elements of the slideway bearing surfaces '23, 24 engaged by surfaces 23, 2i extend parallel with a plane 25 which contains the axis 26"of the crank I5 and. which is perpendicular with the piston axis 22, the same being. also trueof the elements of surfaces 29, 2|. j'lfheislideway C is thus disposed perpendicular to a plane containing the piston axis 22 and the axis 21 of the bearing portions is of the crankshaft sturucture A. The slideway C and bearing block B are important in that they provide. sufficient area to take the high thrusts under. sliding :action without developing undue wearand rattle. The bearing block B, as will be presently more apparent, presents several critical regions such as at its corners or regions 28 which lie immediately adjacent the opposite extremities of the surfaces 23 and 2| in a direction transversely of the piston axis 22, as viewed in Fig; 3.

.Inorder' tojfacilitate assembly or each piston structural), and bearing block structure B with each of "thecranks 6 ofthe one-piececrankshaft structure A, I have 'formed'the piston of a pairof matingor complementary similar halfportionsi23 which are adapted to be bolted togethentoprovide: a rigid double ended piston. Likewise the bearing block structure is formed .of similar or interchangeable complementary half, portions 30,3 I.

Each piston portion 29 comprises a pressure-' receiving head 32,.formed with a skirt 33 depending' therefrom and such; piston portion. is provided with aniX-brace connection between its vhearljskirt, and slideway portion. in the form of a pair of cast "struts or webs '34 and 35. This X-brace serves to rigidly and integrally join one of theslideway bearing surfaces 23, 24 with an associated piston-"head 32 and'skirt portion 33. Each piston portioniZB is further provided with anintermediate bodyportion joined to that of the, other :pis'ton portion 29. This intermediate body portion in the present illustrated embodiment of my invention comprises a plurality of circumferentially spaced'piers or ties 36 extending from each skirt portion 33. The piers of one pistonportion 29 have their end faces engaged with corresponding faces of the piers of the other piston portion, the engagement being in plane 25.

The piers'35 have their outer surfaces 31 cylindrically formed to slidably fit the associated cylinder bore and abutting pairs of piers are pro vided with a passage extending axially of the piston for receiving a tie-bolt 38 tensioned by the heads'39, .accessto which is accommodated by the 'headereceiving piston windows 43. It will be apparentthat the piston structure D asa whole is uniformly cylindrical throughout its length, no portionorjthe piston projecting radially beyond the skirt and pier outer bearing surfaces.

Thel..intermed-iate"hodystructure of each pistonJstructure D. provided with a pair of diametr'ically disposed piston slots. or openings di extending aXiallyJof the piston, these openings bein provided'jbetween the piers 33 which are adjacent the .crankshaft bearing portions I5. .Thejslots'dil receive; the crankshaft A and are so arranged as '.to. provide unobstructed reciprocation of-thepistonand are of minimum length such that when the piston is at its extreme limits of reciprocatory. travel the respective ends of the slots 4] are disposed with minimum practicable clearance withfthe crankshaft structure in order v ignition type.

to attain the. maximum. compactness for the en'- The spaces between adjacent piers136 on the same side of crankshaft 'A define openings 4 l, for the slideway C which extends all the way through the piston structure D. V

Each of the skirt portions 33 is formed with a plurality of ring-receiving grooves opening out-'- wardly toward the cylinder bore for accommodating the desired number of outwardly expanding compression rings, oil rings, and the like indicated at 42, the innermost ring being designated at 43, the location of the latter being of material significance in the more limited aspects of my invention, as will be presentlymore apparent. Each ring is provided withra support land, that for the innermost 'ring being-indicated at 44.? V:

-. The engine cylinder.block'structure E, accordingto my invention is shown disposed such that the cylinders extend horizontallyia's shown in be expressly otherwise set forth in the appended claims. Furthermore, my description will for the most part bedirected to a cylinder and piston assembly which is typical of the remaining :cylinders and pistons of the engine;

' The. block E is formed in mating. component half-portions 45, '45 having planar face contact vertically at plane 41 which passes through the axis 21'of crankshaft structure A. .The component portions 45, .46 are'l'formed with companion cylinder bore portions 48 so that when the block portions" are brought together ea'chpiston D will be slidably contained in what in effect is a single continuous uniform diameter cylinder F open at each .side of the block and'made up of the twocoaxial cylinder bore portions 48, as shown in Fig. 2. The cylinder blockportionsare formed with pairs of mating or companion openings or recesses for receiving: the bearing'portions [5 of the crankshaft structure, as will presently be more apparent; Thus the cylinder block portions together provide'the'openings llii'for rotatably receiving the crankshaft structure. The cylinders F are closed at eachend thereof by a cylinder head'G seated at the side of the portions 45, 46 of block E, each cylinderhead having a plurality of combustion chambers 50 for the multi-cylinder engine illustrated?v Each combustionchamber closes one end of a cylinder F andis provided with the usual sparkplug 5| where the engine is of-the conventional spark The engine illustrated .:is :of the four-stroke cycle type having a camshaft structure 52 e'x-'- tending longitudinally of the engine and driven from'one end ofthe crankshaft by gears 53, 54 in Fig. 4. The camshaft has its'axis 55 inthe plane 41 and is journalled in bearings 56 located 7 at intervals above the crankshaft bearing .por-

tions I5 and in suitable mating or. companion openings or recesses in the portions 45, 46 of block E. The camshaft operates intake and exhaust valves 51 and 58 respectivelyjit being understood that each combustion chamber 50 has an upward-. ly extending valve-receiving portion 59 'accommodating the lift of a set ofval'ves 51, 58' for controlling the fuel mixture intake to the chamber and the discharge of exhaust gases therefrom as is Well known for four stroke cycle engines in general. Each'of the componentzcylinde'r block portions is provided with intake and exhaust valve seats 60 and 6| engaged by the respective valves 51 and 58. V

The valves 51, have their, stems 62 extending toward camshaft 52 for operation by camfollowers or tappets 63, a spring 64 yieldingly seating each valve and maintaining the tappets in contact with the various cams 65 of the camshaft 52. The block portions 45, 46 are provided with intake and exhaust passageways 66, '61 extending from the seats 60 and 6| of the respective intake and exhaust valves 51, 58 upwardly so as to open at the upper faces ofblock portions 45, 46 for communication with conventional intake and exhaust manifolds (not shown).

As each piston structure D reciprocates in its cylinder F, the bearing block B slides back and forth in the slideway C while transferring the reciprocatory movement of the. piston structure into rotation of the crankshaft'structureA by reason of the crank' portion l5 being journalled in the bearing I8. In order to allow for selfadjustment of these operating parts and to compensate for any minor misalignments in the assembly as well as to improve the efficiency and general'operating. characteristics of the piston andcrankshaft connection, each pair of sliding bearing surfaces 20, 23 and 2|,224 are formed as portions of cylindrical surfaces having a common axis 68 as the axis of such cylinders. Thisaxis 68 is contained in plane 25 and is normal to axes 22 and 26. Whenthepiston structure. D is at each of its extreme positions of movement 'out-' wardly of its cylinder then therthree axes 22, 26, and 68 intersect at a common point as seen in Fig. 5 for example. The bearing .block structure B is not confined to small amounts .of movement axially on crank 16 in the direction ofthe crank axis 26 and, therefore, the cylindrical bearing surfaces 20, 23, and 2|, 24 will act to center the bearing block structure B on the crankili. The bearing block structure B is freeto adjust itself between the piston and crankshaft? structures to relieve binding which {might otherwise result from minor inaccuraciesof machiningland assembling of the parts. I

The bearing structure B is formed, for convenience of assembly, of a pair of similar interchangeable. portions 36, 3| provided internally with the complementary semi-cylindrical portions 'of the aforesaid cylindrical bearing surface of revolution l9 surrounding the cylindrical bearing surface of crank l6 and having a journal bearing fit therewith. Bearing, surface i9 is developed or generated about the axis. 25 of the bearing surface of the crank I6.

Each of the bearing block portions 35, 31 is provided with a connecting portion 69 at opposite sides of and; adjacent its semi-cylindrical portion of bearing I9. and each portion 69 isperforated at 10 on an 'axis parallelwith the axis 22 of thepiston structure D. The connecting portions 69 constitute portions or regions intermediate the corner regions 28 in a direction axial= 1y of'the piston structure, When the bearing block portions 30, 3! are assembled theperforations 10 of 'the connecting portions 69 are in alignment with, eachpther at the opposite sides of bearing l9 to receive the headed connecting members H which maintain portions 30, 3i assembled with their portions 69 in contact. With 7 ieach nthermniplanemormal'zto' axis :22..=and..containing axiszfifi.v

. themodified. fIGlIHLOf. bearing. :blo'ck' shinetureIBiillustrated:in.Eigs. l2;and.;13,:;the and interchangeable block portions 39 land :34 have :their connecting or intermediate: body gportions 69' disposed as aforesaidforportions, 63 but differing therefromfin that the connecting portions 69 :are of hinge-likezformation. Thus each portion 69 has a centrally disposed hinge projection '12..at..one side. and a pair of :axia'lly spaced. apart hinge projections 13 iattzits oppositev side, :the projections 'land 13 being perforated at Hli. .Dn assembly aconnecting .mem her or pin I6 is passed through the aligned perforations of a'projection 1.2 and ap'air of projections .13 thereby iforming the. bearing structure B as arigid 'unitpprojection. flitting into the :space between projections 13:.and.thelaxes ofspins is extending parallel with the 22 of. the 'piston structurelD. .Otherwise, the lblockiB i is similar inustrnctureiand "function tothe block B in that itisprovidedwith the aforesaid cylin= drical bearing :surfacesifl and. It will hennderstood that the bearing; structures. Bv andB' are illustrative alternatives for use in. the connecting means. between L the piston structure 3 and crankshaft .A.

..As illustrative of practicable. examples of materials forming the partsoi the .operativecom necting .means andnot byrway of limitation, .I have. obtained good results by casting the piston structure D of commercial aluminum alloyordinarily used to: cast pistons in general, the beau ingblockstructureB being. made of steel and having its cylindrical bearing surfaces 123, 2i hardened. The steel crankshaft Ahashardened cranks l6 runningin semicylindrical bearing inserts l8 of appropriate bearing alloy such as commercial copper, lead; and steelemployed in conventional engines for connecting rod and crankshaft main bearings. Ifdesired, thepiston structure B may :also be of cast ironlinstead of aluminum.

In connection "with: hearing block .5, I have i1- lustrated a modification which, if desired, :may be employed in connection with blockB. In the block 13' the cylindrical bearing surfaces 29, 2| are carried byv and formed as apart of a cast iron insert or facing shoe 75 which is secured'to each bearing block portion 30", '31. The shoes 75 are placed in a mold and the aluminum alloy is then poured to form the aluminum block portions 3d, 31. The shoes '15 have enlarged anchors'TiS embedded in the portions 36, 3| during the casting operation of these portions to provide a unitary assembly of each portion and its bearing shoe id. As an example of use with such an arrangement the piston structure D may be formed of aluminum asrafor'esaid, the alumi num portions 30', 3| having their'bearin'g surfaces i9 journalling the hardened steel cranks 16.

While I have not illustrated the pressure lubricating system for the engine, I have shown in Figs. wand 11 one'manner of conducting lubricant from crank pin I6 to slideway C, the bearing block portions 39, 3] having the lubricant passages 11. In Figs. 12 and 13 corresponding passages 11' are supplied from anannular lubricant collecting groove 18. Further details are more particularly set forth-in my copending application Serial No. 16,648, filed March 24, 1945.

For an engine of the liquid-cooledtype, the cylinder heads G have cored chambers '18 (Figs. 3, 6) for the circulation of a coolant, these chambergppeningmt. ilrto 'themored chambers 8D :02 the block portions 45, 46 for surrounding the-{cylinders .F with :thenoolant. Thechambers .80 are open to each ntheriorvcirculation of the coolant :at 18L f I In order to prevent leakage o'f :the coolantaat the plane-4;! where thefblock portions, 46 are brcughtxtogethertin :face "contact, these face portions are preierablylapped and-coated prior to assembly with .11. xcommercialxrubber cement; or other. suitable sealing medium which will permit theblock portions tos'be accuratelyfi'tted together to preserve -the.:nesiredr:relationship.in the .com ponent *pnrtlons..of the" engine elements as, for example,: shes-cylinders and the bearings. fOlithl-E .crankshaftand camshaft. j 1

Iheportions 45,146.0f the-block E .areheld together in assembled relationship, along with the cylinder heads G,; crankshaft LA, and camshaft .52, by az plurality of tie-bolts 582 which extend laterallyall the way through the'component cylinder blocki portions; and the cylinder heads .G, the opposite .headedends of the tieeboltsbeing seated unsuitablefaces'yprovided :by. the outer sides .of..:thel;longitudinal1y extending cylinder heads G.

. In carrying. out myiinvention, '1. have provided certain physical'relatlonships of the variousiparts in order toobtainmaximum. compactness of the engine "which is of the :greatest practicable .importance, :especially: in enabling the. engine :to be constructed with .a unitary crankshaft structure asqcontrasted with: a sectional .or-rbuilt-"up crankshaft structure. ;.Inrautomotive, aircraft, or even stationarypower plant installations, engineers have striven TBOLDIOTVidB an engine which will produce more power-for a given physicalasize, the latter also necessarily including weight :and cost, such compactness being most ;difiicult;to achieve in. a double acting engine having a soiled crankshaft. 'In ..-'automotive .mstallationslsuch compactness. in. engine iconstruc'tions' is. -'of the greatest importance in providing :a minimum of space "for the power: plant and ,a maximum. of space for. the passenger or .loadcompartment as well as aimaximum of space for wheel suspensions, steering mechanism, and other vehicle equipment. This. of course, means that. ifrsuch vehicle :is powered commensurate with standard practice my engine woul-doccupy much lessspace and Would 'be'much lighterand less costlyto manufacture and, at the same time, incorporate the preferred type of "unitary crankshaft.

There are certain'critical relationships o'fcertain of the parts ofa double acting engine, these being interdependent :on each other so that if they are brought together according to myteachings then the desired compactness will result. On the other Thand,.if certain ofthe componentrelationships are not observed, then thisin turn requires such distortion of other of the inherent relationships that the advantages of myinvention cannot be realized, atleastnot to the extent possible by such observance.

In an engine having conventional carburetor type of. aspiration, pressures :in the. combustion chamber are developed, with'fuels of the .most common octane ratingin the orderlof 600 p. s.:'i. (pounds persquareinch) although with supercharging and for high octane "fuels or for diesel engine practice pressures of 1200 p. s. i. and even morezare utilized. .In constructing a double acting engine, itis important thatthe diameter H of the crankshaft bearings I5 shouldbea minimum consistent with allowable stress and bearing loads. For engines of the conventional carburetor aspirator type, by utilizing available commercial forged material for the unitary crankshaft structure A, the ratio of the cylinder bore J to H should be in excess of approximately 2.4, say 2.4 to 2.6. If the ratio is materially higher, then excessive deflection and load are placed on the crankshaft leading to failures at bearings l and at the bearing block B, for example. If this ratio is materially lower, then H is too large in relation to J from a standpoint of necessary strength and, of more importance, such relationship exacts a magnified penalty on the ultimate size, weight, and cost of the engine for a given power output. The general relationship of J in terms of H is as follows: l

J 8 J 2 K L where K is the length of the bearing l5, L is the total allowable stress, and M is the applied pressure on the piston. For good practice, I haveillustrated the bearings I5 as being of a length K equal to half their diameter. A the allowable stress. of the material is about 20,000 p. s. i. it will be found that the ratio of J to H is 2.4. In time other materials may be discovered which will permit this ratio of approximately 2.5 to be increased which will be of advantage in following the teachings of myinvention and in my reference herein. to specific values of such ratio, I naturally contemplate such deviations therefrom as may be made. possible by the utilizing of materials for the crankshaft which may be suitable as well as deviations occasioned by the use of combustion pressures higher thanthe assumed conventional pressure of around 600 p. s. 1. However, for modern practice as. a substitute'for present popular automotive engines the ratio of approximately 2.5 is chosen as being determinative of achieving the improvements set forth herein for purposes of illustratingmy invention. The desired relationships are most diflicult to achieve without resorting to a sectional crankshaft, my invention making it possible to obtain the desired compactness and to assembletheengine with a unitary crankshaft structure A.

With the values of J and H having been determined, the proper stroke of the engine is also determined thereby as'will be presently apparent and is not to be taken as any arbitrary value according to the broader aspects of my invention. I determine the maximumvproper engine stroke for the maximum of compactness as that value which will cause the bearing block B to travel in a path such that the continuity of the cylinder F will not be interrupted outwardly, of the crankshaft axis 21 at a distance greater than the interruption necessarily required for accommodating the crankshaft Awhereby the innermost'piston ring 43 will not. travel over any such interruption in the cylinder wall. As it is generaly desirable to provide the crankpin. IS with asdiameter equal to H, and as the bearing block B surrounds the crankpin, it will be apparent that the sweep of the corner regions 22 of blockB presentscritical limitations to the maximum proper engine stroke. The difficulty is further. increased byreason of the requirement to split the bearing block B and to provide a fastening means for the block halves and to so arrangethe intermediate regions of the block B so that during its swing such regions will not cut the cylinder walls more than, the length of cut or opening 49 required to receive the crankshaft structure A as otherwise,

if rings 43 are to avoid contact with such cuts,-

the pistons must be longer and the width and weight of the engine increased.

The minimum length N as well as the width N of the bearing block C as seen in Fig. 3 should be, from the standpoint of practical considerations, approximately 1.25 times that of the crankpin diameter H. By proportioning the ratio of the bore J to the stroke 0 substantially .2 to 1, while providing adequate ties 36 for the opposite piston heads 32, then the travel of the advancing corner region 28 will describe an arcuate path 84 which, as seen in Fig. 5, will at all times lie within the cylinder bore.

In order to provide a maximum of stroke 0 for a given bore J, and at thesame time provide the desired size of bearing block B and crankpin l5 and to also maintain the piston rings 42, -43 in contact with uninterrupted portions of the walls of cylinder F at all times during operation of the engine, I utilize the length of cylinder walls defined by the crankshaft-receiving openings 48 to accommodate further openings 92, 93 to receiveintermediate portions of the bearing block B during movement of the piston structure D toward and from its mid-stroke positions, which openings are shown in Fig. 6. In the diagram showing of Fig. 5 the block opening- 49 is projected 90 around the cylinder wall into the path of swing of the bearing block-B to illustrate the optimum relationship. In Fig. 5 I have illustrated the paths of swing of several points on the bearing block B and particularly those points which are most critical in tending to cut the cylinder walls the most-distance away in a direction axially of the cylinder, from the mid-region of the cylinder at the plane 41, As will presently be more apparent, no point on the bearing block B cuts the cylinder wallsoutside ofthe projected length 49. Therefore,-if the piston rings are arranged to clear the openings 49 then they will not overlap the openings necessary to accommodate the swinging movement of the bearing block B and atthe same time fasteners H for block B are provided anda solid crankshaft is employed. The most critical region of block B in connection with the path of travel aforesaid; tends to be located at the corner regions 28 and also at the intermediate regions 69. By insuring the travel of regions 28 always within the-cylinder bore itis then possible to so arrange-the parts that all points on the bearing block B intersect the cylinderwalls in the region located within the diameter of the crankshaft-receiving. openings 49.

This represents the optimum relationship for compactness where the piston rings do notovertravel any cylinder openings.

In Fig. 5, the regions 28 are preferably curved at 86 in the direction of the thickness of block B concentrically with the cylinder so that they may swing closely to the cylinder With substantially minimum clearance and without breaking into the cylinder and thereby not penalizing the maximum available stroke. Such clearance can, as a practical matter, be maintained as little as .025 times the diameter of the crank portion. l6 and even less for carefully machined parts and careful assembly. -i-

The travel of the extreme curved element of an advancingregion 28 is illustrated bycircular paths 84 and 85 for the respective points'BS and 81 on such element. *It will be noted thatthese arcs do not cut the cylinder. -In similar manner the travel of twocritical points 88, 8.9 lying at the intermediate region 69 is shown by circular.

paths 99, 95- respectively which cut the cylinder,

The coolant in the cylinder blocksectiens' ifi', I

48 circulates around theopenings 92, 93 and the lower opening 93' is utili'zed'for 'oil drainage as it is open downwardly through the cylinder block portions to drain oil from the region inside the hollow pistonstru'ctureD downwardly into-the reservoir or'oil pan 94 which is attached to the under face of the cylinder block structure E to provide the lubricant sump for the engine. It will be noted that during operation of the piston the openings 92', 93 are at all times opento the interior of the pi'stonstructure D and that the piston" rings 42, 43 always seal the combustion chamber 50- from communication with openings 92, 533. The upper opening- 92 at each cylinder F; as best seen inFig; 4,- places'one of the camshaft chambers 95 incommunication with the interior of a piston structure D for oil drainage from chamber 95 down through the piston and opening 93' to the pan 9 Each camshaft chamber 95 is defined by mating recesses in the block halves 45, 59 and lies between adjacent camshaft bearings 55 to receive therewithin the four cams st for controlling the intake and exhaust valves 5?,- 58 adjacent each end of the-cylinder which is directly below such camshaft chamber.

Theoffset of the crank portion I6 is of such amount' in relationship with the cylinder bore J, and the bearing block structure B and'slideway C are so constructed and arranged, that the regions 28, as well as all other points on the bearing block bearing surfaces 20, 2!, always lie within the. bore? of cylinder F during operation of the engine. The reg-ions 28 'andsuch other points on: the bearing block'bearing surfaces 29, 21 are always disposed outwardly axially oi the bore from parallel planes 96 and 9'! (Figs. 1 and5). These planes are perpendicular to the cylinder axis 22 and are tangent with the crankshaft-- receiving openings $9; By maintaining such relationship: the corner regions 28 and all other points on the bearing block bearing surfaces 29,

2|. will move in such a'path that will not requireinterrupting the cylinder bore axially outwardly from the interruption at 49 necessary to receive the crankshaft structure. Therefore, ifthe piston' rings clear to Openings then they may be disposed to move. close to these openings and yet always slide on uninterrupted'portions of the'cylinder bore even though, at times, the critical corner, regions 28 of the. bearing block structure C and. other points thereon lie outside of the parall'el planes 96 and 91.

It will be noted that the offsetof'the crank p'ortion [6, which determines the stroke O,'is of such predetermined amount in relationship with the diameter J of the cylinder bore F that, during operation of the" engine, each of the oblique portions I Iv of the crankshaft structure A will sweep a path adjacent the intermediate body structure of piston Dsuch that,when thepiston is midway ofv itsstroke as shown inFia' l, suchoblique por'-- atteststionwi'll be-d'i'sposedin a direction transverselyof' ture. My reference to minimum clearahcef will be readilyunderstood as meaning-the usuar-prac tica-l nominal clearance far accommodating necessary-shop t lerance reparations.

In productio'nit usually desirable' to assemble crankshafts' as io'rged Landwithout machining.

except for" the bearing and cranis journals'.

Where such a forged crankshaft structure employed, without machining the outer surfaces of the oblique-'portions'i'lg and-where the piston D is not machined as to these portions adjacent the region of minimum icl'e'arancexlati 98,-; this minimum clearance should .be: 'abonti oneeeigh-tlr of an inch, plus or minusrusualt sh'oprtolerances in order to mostiully reallpexthet advantages of-i my invention. Of course, if thetcrankshafttor' piston is. machined.;at the region; ssithen this Vminimum clearance may; be somewhat? lessen-ed";

The; opposite: head. portions or: portions 2910f; the: piston" must; rofi eourse,-:: be. :connectedrtogether; suiiiciently to maintainxthe desired :ri'gid'ity' oflthe piston-1. to' insurezits rproperaoperation and; thence fore adequatelthicknesscof; material; mustsb'e int-1 paitedtothe pistoniintermediate: bodyss'tructurer When. this *is. eiiecstedg'v certainijnlmherirn-r-t portant objects .ofsmy invention may he. realized.

' by providing the oblique crankshaft; portions I51" quate. thickness ofmateriali around the; embedded:

fasteners 38 so that adequatestrength islimparted tothepistontstructureD; ASz'bBSl? seen inzEi'giAn I have provided az-novelarelatidnshipnbetweenthe piston ties 3t and crankshaftWhichhcontrihutes; in arriving at; the; desired optimumzim compactnes's as set? forthiinidetail: herein-.4; lnaFi'g'le the 7 piers: 36, at leastrimthelregion 'ofiswingiof the obliquer portiomzlzh; haveiitheir; inner: :surfacess conevex'around the fasteners; 31% "and the oblique'por-r tions: 11-: are: correspondingly dished; or: .concavert at; 9 91 bounding the: minimum? clearancereg-ion 98 In 7 order: to provide: substantially; uniform strength in; 'oblique'zzportion :|':|r,1: Lhave icon-.- Strlldtfida such? portion; :of substantially gconstantz or uniform area-tinasections' normal: to: the crank shaft? axis 21 betweenzthe: ends of portion: H at. a: crankzzifi and. bearing;- 15: Eigstflrtoefi illustrate thecOnstruction ofa typical: oblique portion .lT-I; In order" to; prevent unduaweak-eningfof; the: por:-: tion 'I 'l' adjacentthecrankipontioni'lfi thasurfaca region; [99. which is: disposed 1' 80r from the: conxcave: region 99 isfgienerously bulgedoutwardlyias L rings #24 413 it will be noted that they" are 50* disposed; m2 rela tionship with the crankshaft-receiving openings 49, as to always remain in engagement with portions of the cylinder bore which are disposed outwardly of these openings in a direction axially of the bore during operation of the engine.

The innermost piston ring 43 of each piston D is disposed for movement contiguous to the associated crankshaft bearings l and contiguous to the cylinder block openings .49 for such bearings. By so locating these inner. rings the length of the piston is kept .to a minimum and, therefore,.the width of the engine is minimized along with the optimum in compactness; low weight, and low cost. Furthermore, such ring location ina sense determinesthe maximum stroke of the piston as I deem itto be desirable to have the piston rings alwaysengage the'continuously cylindrical uninterrupted wall portions of the cylinder-bore F to openings with consequent damage to the rings, lands, cylinders, and leakage past the rings. Therefore, the rings should not overlap any cylinderopenings at least to such an extent as to give rise-to tendency of the rings to expand into any cylinder openings or to otherwise cause undesired wear of the cylinder and rings and jamming and breakage of these parts. My invention teaches how this is accomplished when a solid crankshaft is employed.

The innermost ring 43 associated with each piston head portion 32 has its inner surface boundary, axiallyof the piston, disposed in a ringsurface I02 which is normal to axis 22 and disposed as shown in Fig. 1 when such piston head portion is at the limit of its stroke inwardly of the cylinder bore. The stroke 0 is such in relationship with thecylinder bore size J and bearing block structure B and slideway C are so constructed and arranged that the corner regions 28 and all other points on the bearing surfaces 20, 2| of block structure B always lie within the cylinder bore during operation of the engine, the end regions 28 and the other points along the bearing surfaces 20, 2| being disposed outwardly axially of said bore from such planes I02.

The bearing block B is thus maintained of minimum length in the direction of slideway C, preferably such that the corner regions 28 remain within the cylinder walls at all times. Inasmuch as openings in the cylinder walls are necessary to journal the crankshaft and inasmuch as I have provided an arrangement which causes the piston rings to avoid overlapping such journal openings, certain of the advantages derived therefrom would be, at least to some extent, lost if the bearing block B was arranged for such movement as to require an opening in the cylinder wall into which the piston rings could expand with destructive results.

Certain of my engines arranged in accordance with my invention provide a bore stroke ratio E of 2.5

- avoidldanger of the rings expanding into cylinder v "14 and 2.6 and a ratio of stroke mic of approximately1.25.

The relationship of is derived from from which 0 ==l.25 v v thus further illustrating the desired relationship of stroke 0 in terms of crankshaft bearing diameter H dependent on a common relationship which each has with the bore J. l l

Any suitable crankshaft throw arrangement may be provided such as in Fig. 6A arrangement of cranks for the four cylinder engine illustrated. Cranks-l and 2 are in the same plane but 180 from each-other. Cranks 3 and 4 are likewise in a common plane and 180 'a'p'art; Thesetwo planes are related from each other. This four cylinder engine is, in effect, an eight cylinder engine as each of-the' four cylinders hereinbefore discussed'in detail provides two combustion chambers each having its. piston head for operating the crankshaft. Obviously any number of cylinders may be used to construct an engine contain the various parts including thevalve gear shown in Fig. 2 and the tie-bolts 82 secured in place.v :m 1 The camshaft bearings 56 are formed in halves for assembly in the mating semi-cylindrical openings I03 (Fig. 4), of the block. portions 45, 46 whereby the camshaft structure 52 is rotatably journalled at its journal. portions 104.

It will be; understood that the bearing-block B may be substituted for block B andwhatihas been said hereinbefore with respect-to block B is equally applicable to block B. The block B is somewhat more compact as to its intermediate regions 69 than block B such that regions can 'be more conveniently located closer to the axis of the crank l6 than the corresponding regions 69. Hence it is somewhat easier in some instances to control the swing of the Fig. 12 hinged type of block with respect to the cylinder walls and the movements discussed in connection with Fig. 5. However, the Fig. 10 arrangement is somewhat preferred for assembly and other reasons.

Engines of various desired capacities may be readily made following the teachings of my invention. Engines having cylinder bores larger than that illustrated will naturally develop more total pressure on the piston with consequent increase in size of crankshaft end bearing dimension H. This would have a tendency to limit the available stroke except for the necessary increase in crankshaft bearing diameter which, in turn, accommodates a stroke of substantially half the bore diameter. As fuels of higher octane rating become more available!orwith superchargedifuel mixture or With diesel cycles, higher compression ratios may be used thus increasing the piston load for a given size cylinder bore and requiring increase in size of crankshaft and dimension H.

This will have the tendency to-sorneWhatsl-iorten the available stroke in relation: tozthe bore and increase the ratio of hereinbefore set forth. However. such ratio will still in the ultimate not greatly exceed the ratio set forth herein and even in such instances the maximum in compactness may be readily obtainedby following the teachingsof my invention.

Features of novelty not-claimed but disclosed in my subject application are more fully disclosed and claimed in the copendingapplications of Alexander G; Herreshoff, SeriaLNo V16-,801,filed March 24, 1948, and John- P. Buttertfield; Serial rotatable crankshaft sti'cucture ;havingv coaxial bearing portions r'otatably supportedinzsaid bloc-k bearing openings and. havingza crankportion 10-- cated between andlofiset from saidbearizig pon and." bore length: and; aligned. with said secondpair" of slots, a bearing block; structure slidably mounted. in said slideway' and rotatably connected. to the crankshaft crankiportion for operably connecting saidpistonand crankshaftstructure,said.

bearing block: structura' said. slideway, and .said crankshaft crank being; so constructed: :and ar: ranged. that the slidable bearing. surfaces of the bearing block; alwaysslie within said cylinderibore' during operation or the: engine whilexa'nyzother.

portions otsaid bearing block that cut'thewalls or said cylinder bore' durin crankshaft rotation pass through said second pair: of slots in;th'e' pis-v ton, engine: operating mechanism superimposed on said cylinder block and contained in 'a'cham berthat extends transversely oithe'cyli'nder-bore, fluid flow lubrication means forsaid" ei'igine oper ating mechanisminsaid chamber; and a'pairrof tions and of such size and shape-"as tome-Loomtinuously disposed within: said cylinder: bore during rotation of the'crankshaft, at double ended piston mounted. in said cylinder -bore'forrec'iprocation lengthwise thereof, said" pistonhaving conduits formed in: said cylinderblock and. aligned with said second pair of slots in said piston in termediate body structure, one of 'said'conduit's connecting said chamber'to'said second pair of slots in said piston and to said cylinder-bore and the other of said pair of conduits connectin said second pair of piston slots and saidcylinder bore to a' liib'ri'cant' receiving sump.

JOHN PI BUTTERFIELDQ REFERENCES CITED The following references are of record intl'i'e filc or" this patent:

UNITED STATES PATENTSv Number Name Date 1,042,505 'l'wornbly Oct. 29-; 1912 1,047,860 Tvvombly Dec; 17, 1912 1,140,292 Sharpnecketa1. May'1'8', 1915 1,210,996 Slate Jan. 2", 1 .917 1,274,813 Sullivan Aug; 6, 1918 1,287,509 Sullivan Dec. 10, 19-18 1,287,797 Tietzmann Dec1'1-7, 1918' 1,578,228 Yearsley Mar. 23,1926 1,735,707 Worden Nov; 12, 1929- 2,038,085 Ross"; Apr 21, 1936 2,170,099 Stubings .1 Aug; 22, 1939 2,337,157 Finley et a1. a D'd'ZI, 1943' 2,404,906 Heald Jul '30, 1 946 FQREIGN PATENTS Number Country Date 393,606 France s OCt.l30, 1908 772,815 France ..Nov. 7, 1934 

